Optical signals are useful for many applications in modern communications systems. A typical optical communications system comprises a transmitter of optical signals (e.g., a laser-based transmitter that generates a desirable wavelength of light, such as 1550 nm), a length of transmission optical fiber coupled to the source, and a receiver coupled to the fiber for receiving the signals. One or more amplifying systems may be disposed along the fiber for amplifying the transmitted signal. Within the receiver or other components within such systems it is often desirable to split the propagation of a single optical light beam into two or more split light beams propagating in different directions (e.g., to different photodetectors). Optical beamsplitters have traditionally been used to accomplish this beam splitting function.
Typical optical beamsplitters are, illustratively, semi-reflective cubes and/or plates placed in the path of a propagating beam at a desired preset incidence angle relative to the beam. When positioned at such an incidence angle, the input beam arrives at the partially reflective surface of the beamsplitter at a certain angle in a way such that a portion of the beam is reflected in one direction while at least one other portion of the beam is permitted to pass through the beamsplitter in another direction. As one skilled in the art will recognize, the performance of these types of beamsplitters typically depends to a large degree on precise positioning of the beamsplitter in relation to the incoming light beam and the destination optical components.